/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.nuatar.meibi.tool;

import java.io.UnsupportedEncodingException;
import java.util.Arrays;

/**
 *
 * @author AnchLi
 */
public class Base64 {
	  private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
	          .toCharArray();
	  private static final int[] IA = new int[256];
	  static {
	      Arrays.fill(IA, -1);
	      for (int i = 0, iS = CA.length; i < iS; i++)
	          IA[CA[i]] = i;
	      IA['='] = 0;
	  }

	  // ****************************************************************************************
	  // * char[] version
	  // ****************************************************************************************

	  /**
	   * Encodes a raw byte array into a BASE64 <code>char[]</code>
	   * representation i accordance with RFC 2045.
	   * 
	   * @param sArr
	   *            The bytes to convert. If <code>null</code> or length 0 an
	   *            empty array will be returned.
	   * @param lineSep
	   *            Optional "\r\n" after 76 characters, unless end of file.<br>
	   *            No line separator will be in breach of RFC 2045 which
	   *            specifies max 76 per line but will be a little faster.
	   * @return A BASE64 encoded array. Never <code>null</code>.
	   */
	  public final static char[] encodeToChar(byte[] sArr, boolean lineSep) {
	      // Check special case
	      int sLen = sArr != null ? sArr.length : 0;
	      if (sLen == 0)
	          return new char[0];

	      int eLen = (sLen / 3) * 3; // Length of even 24-bits.
	      int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
	      int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of
	                                                              // returned
	                                                              // array
	      char[] dArr = new char[dLen];

	      // Encode even 24-bits
	      for (int s = 0, d = 0, cc = 0; s < eLen;) {
	          // Copy next three bytes into lower 24 bits of int, paying attension
	          // to sign.
	          int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8
	                  | (sArr[s++] & 0xff);

	          // Encode the int into four chars
	          dArr[d++] = CA[(i >>> 18) & 0x3f];
	          dArr[d++] = CA[(i >>> 12) & 0x3f];
	          dArr[d++] = CA[(i >>> 6) & 0x3f];
	          dArr[d++] = CA[i & 0x3f];

	          // Add optional line separator
	          if (lineSep && ++cc == 19 && d < dLen - 2) {
	              dArr[d++] = '\r';
	              dArr[d++] = '\n';
	              cc = 0;
	          }
	      }

	      // Pad and encode last bits if source isn't even 24 bits.
	      int left = sLen - eLen; // 0 - 2.
	      if (left > 0) {
	          // Prepare the int
	          int i = ((sArr[eLen] & 0xff) << 10)
	                  | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);

	          // Set last four chars
	          dArr[dLen - 4] = CA[i >> 12];
	          dArr[dLen - 3] = CA[(i >>> 6) & 0x3f];
	          dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';
	          dArr[dLen - 1] = '=';
	      }
	      return dArr;
	  }

	  /**
	   * Decodes a BASE64 encoded char array. All illegal characters will be
	   * ignored and can handle both arrays with and without line separators.
	   * 
	   * @param sArr
	   *            The source array. <code>null</code> or length 0 will return
	   *            an empty array.
	   * @return The decoded array of bytes. May be of length 0. Will be
	   *         <code>null</code> if the legal characters (including '=') isn't
	   *         divideable by 4. (I.e. definitely corrupted).
	   */
	  public final static byte[] decode(char[] sArr) {
	      // Check special case
	      int sLen = sArr != null ? sArr.length : 0;
	      if (sLen == 0)
	          return new byte[0];

	      // Count illegal characters (including '\r', '\n') to know what size the
	      // returned array will be,
	      // so we don't have to reallocate & copy it later.
	      int sepCnt = 0; // Number of separator characters. (Actually illegal
	                      // characters, but that's a bonus)
	      for (int i = 0; i < sLen; i++)
	          // If input is "pure" (I.e. no line separators or illegal chars)
	          // base64 this loop can be commented out.
	          if (IA[sArr[i]] < 0)
	              sepCnt++;

	      // Check so that legal chars (including '=') are evenly divideable by 4
	      // as specified in RFC 2045.
	      if ((sLen - sepCnt) % 4 != 0)
	          return null;

	      int pad = 0;
	      for (int i = sLen; i > 1 && IA[sArr[--i]] <= 0;)
	          if (sArr[i] == '=')
	              pad++;

	      int len = ((sLen - sepCnt) * 6 >> 3) - pad;

	      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

	      for (int s = 0, d = 0; d < len;) {
	          // Assemble three bytes into an int from four "valid" characters.
	          int i = 0;
	          for (int j = 0; j < 4; j++) { // j only increased if a valid char
	                                          // was found.
	              int c = IA[sArr[s++]];
	              if (c >= 0)
	                  i |= c << (18 - j * 6);
	              else
	                  j--;
	          }
	          // Add the bytes
	          dArr[d++] = (byte) (i >> 16);
	          if (d < len) {
	              dArr[d++] = (byte) (i >> 8);
	              if (d < len)
	                  dArr[d++] = (byte) i;
	          }
	      }
	      return dArr;
	  }

	  /**
	   * Decodes a BASE64 encoded char array that is known to be resonably well
	   * formatted. The method is about twice as fast as {@link #decode(char[])}.
	   * The preconditions are:<br> + The array must have a line length of 76
	   * chars OR no line separators at all (one line).<br> + Line separator must
	   * be "\r\n", as specified in RFC 2045 + The array must not contain illegal
	   * characters within the encoded string<br> + The array CAN have illegal
	   * characters at the beginning and end, those will be dealt with
	   * appropriately.<br>
	   * 
	   * @param sArr
	   *            The source array. Length 0 will return an empty array.
	   *            <code>null</code> will throw an exception.
	   * @return The decoded array of bytes. May be of length 0.
	   */
	  public final static byte[] decodeFast(char[] sArr) {
	      // Check special case
	      int sLen = sArr.length;
	      if (sLen == 0)
	          return new byte[0];

	      int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

	      // Trim illegal chars from start
	      while (sIx < eIx && IA[sArr[sIx]] < 0)
	          sIx++;

	      // Trim illegal chars from end
	      while (eIx > 0 && IA[sArr[eIx]] < 0)
	          eIx--;

	      // get the padding count (=) (0, 1 or 2)
	      int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count
	                                                                          // '='
	                                                                          // at
	                                                                          // end.
	      int cCnt = eIx - sIx + 1; // Content count including possible
	                                  // separators
	      int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;

	      int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded
	                                                  // bytes
	      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

	      // Decode all but the last 0 - 2 bytes.
	      int d = 0;
	      for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
	          // Assemble three bytes into an int from four "valid" characters.
	          int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12
	                  | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

	          // Add the bytes
	          dArr[d++] = (byte) (i >> 16);
	          dArr[d++] = (byte) (i >> 8);
	          dArr[d++] = (byte) i;

	          // If line separator, jump over it.
	          if (sepCnt > 0 && ++cc == 19) {
	              sIx += 2;
	              cc = 0;
	          }
	      }

	      if (d < len) {
	          // Decode last 1-3 bytes (incl '=') into 1-3 bytes
	          int i = 0;
	          for (int j = 0; sIx <= eIx - pad; j++)
	              i |= IA[sArr[sIx++]] << (18 - j * 6);

	          for (int r = 16; d < len; r -= 8)
	              dArr[d++] = (byte) (i >> r);
	      }

	      return dArr;
	  }

	  // ****************************************************************************************
	  // * byte[] version
	  // ****************************************************************************************

	  /**
	   * Encodes a raw byte array into a BASE64 <code>byte[]</code>
	   * representation i accordance with RFC 2045.
	   * 
	   * @param sArr
	   *            The bytes to convert. If <code>null</code> or length 0 an
	   *            empty array will be returned.
	   * @param lineSep
	   *            Optional "\r\n" after 76 characters, unless end of file.<br>
	   *            No line separator will be in breach of RFC 2045 which
	   *            specifies max 76 per line but will be a little faster.
	   * @return A BASE64 encoded array. Never <code>null</code>.
	   */
	  public final static byte[] encodeToByte(byte[] sArr, boolean lineSep) {
	      // Check special case
	      int sLen = sArr != null ? sArr.length : 0;
	      if (sLen == 0)
	          return new byte[0];

	      int eLen = (sLen / 3) * 3; // Length of even 24-bits.
	      int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
	      int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of
	                                                              // returned
	                                                              // array
	      byte[] dArr = new byte[dLen];

	      // Encode even 24-bits
	      for (int s = 0, d = 0, cc = 0; s < eLen;) {
	          // Copy next three bytes into lower 24 bits of int, paying attension
	          // to sign.
	          int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8
	                  | (sArr[s++] & 0xff);

	          // Encode the int into four chars
	          dArr[d++] = (byte) CA[(i >>> 18) & 0x3f];
	          dArr[d++] = (byte) CA[(i >>> 12) & 0x3f];
	          dArr[d++] = (byte) CA[(i >>> 6) & 0x3f];
	          dArr[d++] = (byte) CA[i & 0x3f];

	          // Add optional line separator
	          if (lineSep && ++cc == 19 && d < dLen - 2) {
	              dArr[d++] = '\r';
	              dArr[d++] = '\n';
	              cc = 0;
	          }
	      }

	      // Pad and encode last bits if source isn't an even 24 bits.
	      int left = sLen - eLen; // 0 - 2.
	      if (left > 0) {
	          // Prepare the int
	          int i = ((sArr[eLen] & 0xff) << 10)
	                  | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);

	          // Set last four chars
	          dArr[dLen - 4] = (byte) CA[i >> 12];
	          dArr[dLen - 3] = (byte) CA[(i >>> 6) & 0x3f];
	          dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
	          dArr[dLen - 1] = '=';
	      }
	      return dArr;
	  }

	  /**
	   * Decodes a BASE64 encoded byte array. All illegal characters will be
	   * ignored and can handle both arrays with and without line separators.
	   * 
	   * @param sArr
	   *            The source array. Length 0 will return an empty array.
	   *            <code>null</code> will throw an exception.
	   * @return The decoded array of bytes. May be of length 0. Will be
	   *         <code>null</code> if the legal characters (including '=') isn't
	   *         divideable by 4. (I.e. definitely corrupted).
	   */
	  public final static byte[] decode(byte[] sArr) {
	      // Check special case
	      int sLen = sArr.length;

	      // Count illegal characters (including '\r', '\n') to know what size the
	      // returned array will be,
	      // so we don't have to reallocate & copy it later.
	      int sepCnt = 0; // Number of separator characters. (Actually illegal
	                      // characters, but that's a bonus)
	      for (int i = 0; i < sLen; i++)
	          // If input is "pure" (I.e. no line separators or illegal chars)
	          // base64 this loop can be commented out.
	          if (IA[sArr[i] & 0xff] < 0)
	              sepCnt++;

	      // Check so that legal chars (including '=') are evenly divideable by 4
	      // as specified in RFC 2045.
	      if ((sLen - sepCnt) % 4 != 0)
	          return null;

	      int pad = 0;
	      for (int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0;)
	          if (sArr[i] == '=')
	              pad++;

	      int len = ((sLen - sepCnt) * 6 >> 3) - pad;

	      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

	      for (int s = 0, d = 0; d < len;) {
	          // Assemble three bytes into an int from four "valid" characters.
	          int i = 0;
	          for (int j = 0; j < 4; j++) { // j only increased if a valid char
	                                          // was found.
	              int c = IA[sArr[s++] & 0xff];
	              if (c >= 0)
	                  i |= c << (18 - j * 6);
	              else
	                  j--;
	          }

	          // Add the bytes
	          dArr[d++] = (byte) (i >> 16);
	          if (d < len) {
	              dArr[d++] = (byte) (i >> 8);
	              if (d < len)
	                  dArr[d++] = (byte) i;
	          }
	      }

	      return dArr;
	  }

	  /**
	   * Decodes a BASE64 encoded byte array that is known to be resonably well
	   * formatted. The method is about twice as fast as {@link #decode(byte[])}.
	   * The preconditions are:<br> + The array must have a line length of 76
	   * chars OR no line separators at all (one line).<br> + Line separator must
	   * be "\r\n", as specified in RFC 2045 + The array must not contain illegal
	   * characters within the encoded string<br> + The array CAN have illegal
	   * characters at the beginning and end, those will be dealt with
	   * appropriately.<br>
	   * 
	   * @param sArr
	   *            The source array. Length 0 will return an empty array.
	   *            <code>null</code> will throw an exception.
	   * @return The decoded array of bytes. May be of length 0.
	   */
	  public final static byte[] decodeFast(byte[] sArr) {
	      // Check special case
	      int sLen = sArr.length;
	      if (sLen == 0)
	          return new byte[0];

	      int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

	      // Trim illegal chars from start
	      while (sIx < eIx && IA[sArr[sIx] & 0xff] < 0)
	          sIx++;

	      // Trim illegal chars from end
	      while (eIx > 0 && IA[sArr[eIx] & 0xff] < 0)
	          eIx--;

	      // get the padding count (=) (0, 1 or 2)
	      int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count
	                                                                          // '='
	                                                                          // at
	                                                                          // end.
	      int cCnt = eIx - sIx + 1; // Content count including possible
	                                  // separators
	      int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;

	      int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded
	                                                  // bytes
	      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

	      // Decode all but the last 0 - 2 bytes.
	      int d = 0;
	      for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
	          // Assemble three bytes into an int from four "valid" characters.
	          int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12
	                  | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

	          // Add the bytes
	          dArr[d++] = (byte) (i >> 16);
	          dArr[d++] = (byte) (i >> 8);
	          dArr[d++] = (byte) i;

	          // If line separator, jump over it.
	          if (sepCnt > 0 && ++cc == 19) {
	              sIx += 2;
	              cc = 0;
	          }
	      }

	      if (d < len) {
	          // Decode last 1-3 bytes (incl '=') into 1-3 bytes
	          int i = 0;
	          for (int j = 0; sIx <= eIx - pad; j++)
	              i |= IA[sArr[sIx++]] << (18 - j * 6);

	          for (int r = 16; d < len; r -= 8)
	              dArr[d++] = (byte) (i >> r);
	      }

	      return dArr;
	  }

	  // ****************************************************************************************
	  // * String version
	  // ****************************************************************************************

	  /**
	   * Encodes a raw byte array into a BASE64 <code>String</code>
	   * representation i accordance with RFC 2045.
	   * 
	   * @param sArr
	   *            The bytes to convert. If <code>null</code> or length 0 an
	   *            empty array will be returned.
	   * @param lineSep
	   *            Optional "\r\n" after 76 characters, unless end of file.<br>
	   *            No line separator will be in breach of RFC 2045 which
	   *            specifies max 76 per line but will be a little faster.
	   * @return A BASE64 encoded array. Never <code>null</code>.
	   */
	  public final static String encodeToString(byte[] sArr, boolean lineSep) {
	      // Reuse char[] since we can't create a String incrementally anyway and
	      // StringBuffer/Builder would be slower.
	      return new String(encodeToChar(sArr, lineSep));
	  }
	  
	  public final static String encode(String s) {
	      // Reuse char[] since we can't create a String incrementally anyway and
	      // StringBuffer/Builder would be slower.
	      try {
	          return new String(encodeToChar(s.getBytes("UTF-8"), false));
	      } catch (UnsupportedEncodingException e) {
	          System.err.println("Base64 encoding error: " + e.getMessage());
	          e.printStackTrace();
	      }
	      return null;
	  }

	  /**
	   * Decodes a BASE64 encoded <code>String</code>. All illegal characters
	   * will be ignored and can handle both strings with and without line
	   * separators.<br>
	   * <b>Note!</b> It can be up to about 2x the speed to call
	   * <code>decode(str.toCharArray())</code> instead. That will create a
	   * temporary array though. This version will use <code>str.charAt(i)</code>
	   * to iterate the string.
	   * 
	   * @param str
	   *            The source string. <code>null</code> or length 0 will return
	   *            an empty array.
	   * @return The decoded array of bytes. May be of length 0. Will be
	   *         <code>null</code> if the legal characters (including '=') isn't
	   *         divideable by 4. (I.e. definitely corrupted).
	   */
	  public final static byte[] decode(String str, boolean used) {
	      // Check special case
	      int sLen = str != null ? str.length() : 0;
	      if (sLen == 0)
	          return new byte[0];

	      // Count illegal characters (including '\r', '\n') to know what size the
	      // returned array will be,
	      // so we don't have to reallocate & copy it later.
	      int sepCnt = 0; // Number of separator characters. (Actually illegal
	                      // characters, but that's a bonus)
	      for (int i = 0; i < sLen; i++)
	          // If input is "pure" (I.e. no line separators or illegal chars)
	          // base64 this loop can be commented out.
	          if (IA[str.charAt(i)] < 0)
	              sepCnt++;

	      // Check so that legal chars (including '=') are evenly divideable by 4
	      // as specified in RFC 2045.
	      if ((sLen - sepCnt) % 4 != 0)
	          return null;

	      // Count '=' at end
	      int pad = 0;
	      for (int i = sLen; i > 1 && IA[str.charAt(--i)] <= 0;)
	          if (str.charAt(i) == '=')
	              pad++;

	      int len = ((sLen - sepCnt) * 6 >> 3) - pad;

	      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

	      for (int s = 0, d = 0; d < len;) {
	          // Assemble three bytes into an int from four "valid" characters.
	          int i = 0;
	          for (int j = 0; j < 4; j++) { // j only increased if a valid char
	                                          // was found.
	              int c = IA[str.charAt(s++)];
	              if (c >= 0)
	                  i |= c << (18 - j * 6);
	              else
	                  j--;
	          }
	          // Add the bytes
	          dArr[d++] = (byte) (i >> 16);
	          if (d < len) {
	              dArr[d++] = (byte) (i >> 8);
	              if (d < len)
	                  dArr[d++] = (byte) i;
	          }
	      }
	      return dArr;
	  }

	  /**
	   * Decodes a BASE64 encoded string that is known to be resonably well
	   * formatted. The method is about twice as fast as {@link #decode(String)}.
	   * The preconditions are:<br> + The array must have a line length of 76
	   * chars OR no line separators at all (one line).<br> + Line separator must
	   * be "\r\n", as specified in RFC 2045 + The array must not contain illegal
	   * characters within the encoded string<br> + The array CAN have illegal
	   * characters at the beginning and end, those will be dealt with
	   * appropriately.<br>
	   * 
	   * @param s
	   *            The source string. Length 0 will return an empty array.
	   *            <code>null</code> will throw an exception.
	   * @return The decoded array of bytes. May be of length 0.
	   */
	  public final static byte[] decodeFast(String s) {
	      // Check special case
	      int sLen = s.length();
	      if (sLen == 0)
	          return new byte[0];

	      int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

	      // Trim illegal chars from start
	      while (sIx < eIx && IA[s.charAt(sIx) & 0xff] < 0)
	          sIx++;

	      // Trim illegal chars from end
	      while (eIx > 0 && IA[s.charAt(eIx) & 0xff] < 0)
	          eIx--;

	      // get the padding count (=) (0, 1 or 2)
	      int pad = s.charAt(eIx) == '=' ? (s.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count
	                                                                                  // '='
	                                                                                  // at
	                                                                                  // end.
	      int cCnt = eIx - sIx + 1; // Content count including possible
	                                  // separators
	      int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1
	              : 0;

	      int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded
	                                                  // bytes
	      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

	      // Decode all but the last 0 - 2 bytes.
	      int d = 0;
	      for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
	          // Assemble three bytes into an int from four "valid" characters.
	          int i = IA[s.charAt(sIx++)] << 18 | IA[s.charAt(sIx++)] << 12
	                  | IA[s.charAt(sIx++)] << 6 | IA[s.charAt(sIx++)];

	          // Add the bytes
	          dArr[d++] = (byte) (i >> 16);
	          dArr[d++] = (byte) (i >> 8);
	          dArr[d++] = (byte) i;

	          // If line separator, jump over it.
	          if (sepCnt > 0 && ++cc == 19) {
	              sIx += 2;
	              cc = 0;
	          }
	      }

	      if (d < len) {
	          // Decode last 1-3 bytes (incl '=') into 1-3 bytes
	          int i = 0;
	          for (int j = 0; sIx <= eIx - pad; j++)
	              i |= IA[s.charAt(sIx++)] << (18 - j * 6);

	          for (int r = 16; d < len; r -= 8)
	              dArr[d++] = (byte) (i >> r);
	      }

	      return dArr;
	  }
	  
	  public static String decode(String s) throws UnsupportedEncodingException {
	      return new String(Base64.decodeFast(s), "UTF-8");
	  }
	  
	  
	 }